Redis example

Gemfile

# Gemfile

gem 'redis', '~> 3.0.1'
gem 'hiredis', '~> 0.4.5'

post.rb

# app/models/post.rb

class Post < ActiveRecord::Base
  after_create :store_in_recent_list
  
  def store_in_recent_list
    $redis.lpush('recent_posts', self.id)
    $redis.rpop('recent_posts')
  end
  
  def self.recent_posts
    ids = $redis.lrange('recent_posts', 0, 19)
    Post.where(id: ids)
  end
end

redis.rb

# config/initializers/redis.rb

$redis = Redis.new(ENV['REDISTOGO_URL'])